JPH02141249A - Ink-jet recording device - Google Patents

Abstract

PURPOSE:To determine optimal discharge intervals in response to the number of the discharge of ink, and to prevent the decrease of printing speed and the increase of the consumption of ink by receiving a printing data, measuring the number of printing dots in the printing data received or the state of the distribution of the printing dots and controlling the drive of an ink discharge means on the basis of the state of the distribution. CONSTITUTION:When printing operation is started, picture data corresponding to one raster are received, printing dots in the picture data are counted by a counter 13a, and the values are added gradually to the total number Nb of the printing dots. When the picture data are received only by raster sections corresponding to the number of the discharge openings of a printing head, the printing data are transferred to a recording head 2 while a carriage 3 is moved and the picture data are scanned, and the dot forming element of the recording head 2 is driven and recording pictures are shaped gradually onto a recording medium such as a blank form. When printing corresponding to one line is completed at that time, the carriage 3 is shifted to a home position when the total number Nb of the printing dots reaches a set value Np requiring the discharge of ink from the discharge openings, and ink is sucked and discharged from each discharge opening by driving a discharge means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording apparatus, and more particularly to an inkjet recording apparatus having a discharge means for removing air bubbles generated in an ink passage within a recording head.

[Conventional technology]

Recording devices such as printers and facsimile machines can be classified into thermal types, wire dot types, inkjet types, laser beam types, etc. depending on the recording method.

Also, depending on the scanning method used during recording, there are three types: serial type, in which the recording head is mounted on a carriage and main scans in the direction of the printing digits, line print type, in which one line is recorded at the same time, and page print type, in which one page is recorded all at once. be able to.

The above-mentioned inkjet recording device records an image on a recording medium (paper, etc.) by ejecting ink droplets from the ejection orifices by driving a recording head having ejection orifices based on print data. It is configured.

The present invention relates to the above-mentioned inkjet recording apparatus, and is applicable regardless of the scanning method, such as a serial type, line print type, or page print type.

In this type of inkjet recording apparatus, a discharge means is periodically driven (ink is discharged from the discharge port by a pressure pump or a suction pump) to eliminate discharge failure of the recording head.

As a result of repeated experiments, the inventors of the present invention found that, in particular, inkjet recording devices using the so-called bubble jet (BJ) method use thermal energy as the energy used for ejecting ink, so depending on the environmental conditions, ink ejection may not be possible. It has been found that bubbles generated from dissolved gas may accumulate in the recording head due to residual heat, and if ink is ejected more than a certain number of times, there is a risk of unstable ejection or non-ejection.

The ejection means can be driven by two methods: one is provided with a function (suction pump) for sucking ink from the ejection port side on the front surface of the recording head, and the other is provided with a pressurizing function (pressure pump) on the ink supply path to the head. It has been known.

[Problems to be Solved by the Invention] Incidentally, in a conventional ink jet recording apparatus, the ejection means is driven at regular time intervals set for each recording apparatus.

However, in such a method of driving the discharge means at regular intervals, the amount of bubbles in the recording head depends on the number of times ink droplets are ejected. If this is determined, more ink will be discharged than necessary when performing normal printing with many white backgrounds, resulting in problems such as a decrease in printing speed and an increase in ink consumption.

An object of the present invention is to solve the above-mentioned problems of the conventional technology, to determine the optimum ejection interval according to the number of times ink is ejected from the ejection port, and to prevent a decrease in printing speed and an increase in the amount of ink erased. An object of the present invention is to provide an inkjet recording device that can perform the following steps.

[Means for solving problems]

The present invention provides ink droplets from the ejection ports by supplying ink to a recording head having an ejection port and driving energy generating means for ejecting the ink provided in the print head based on print data. An inkjet recording apparatus that forms a recorded image on a recording medium by ejecting ink includes means for receiving print data, means for measuring the number of print dots or the distribution state of print dots in the received print data, and a means for ejecting ink from the ejection port. The above object is achieved by an inkjet recording device characterized by having a discharge means for discharging the print dots, and a means for controlling the drive of the discharge means based on the number of printed dots or the distribution state of the print dots. .

〔Example〕

The present invention will be specifically described below with reference to the drawings.

FIG. 1 is a perspective view of essential parts of an inkjet recording apparatus embodying the present invention.

In Fig. 1, l indicates the chassis (frame body) of the recording device;
2 is a recording head (inkjet head) having an ejection port for discharging ink droplets on the front, 3 is a carriage mounting the recording head, 4 is a rail that guides the carriage, and 5 is a guide shaft that guides and supports the carriage. , 6 is a paper foot roller (transport roller), 7 is a pinch roller, 8 is a flexible cable that connects the main body board and the circuit on the carriage, and 9 is a supply of ink from the ink tank on the device main body side to the recording head. 10 tubes
1A and 1B respectively show suction pumps that suck ink from each ejection port on the front surface of the capped (sealed) recording head.

For example, the recording head 2 is provided with 128 ejection ports arranged vertically, and in the case of a bubble jet type, 128 inkjet nozzles are provided with each ejection port serving as a front end opening.

The carriage 3 is supported by a rail 4 and a guide shaft 5 so as to be able to reciprocate in the printing column direction, and the recording head 2 is scanned by the movement of the carriage 3.

Paper feed roller 6 and pinch roller 7 convey the recording sheet in the vertical direction.

The flexible cable 8 is for transmitting signals for controlling the recording head 2, and the ink supply tube 9 is for supplying ink to the recording head 2.

The suction pump 10 is for suctioning ink from the discharge port on the front surface of the recording head 2, and is arranged so that it can come into close contact (capping) with the recording head at a position outside the recording range of the carriage 3 (home position) and be separated from the recording head. has been done.

In this way, ink is supplied to the recording head 2 having an ejection port, and by driving the energy generating means for ejecting ink provided in the recording head 2 based on print data, ink droplets are generated from the ejection. An inkjet recording apparatus is configured to form a recorded image on a recording medium (recording medium such as paper or a thin plastic plate) by ejecting ink.

The inkjet recording apparatus according to the present invention includes means for receiving print data transferred from a host computer or the like, means for measuring the number of print dots or the distribution state of print dots in the received print data, and the ejection port. The apparatus further includes a discharge means for discharging ink, and a means for controlling driving of the discharge means based on the number of printed dots or the distribution state of the printed dots.

The control means for controlling the ejection means may be one that controls the drive interval of the ejection means based on a predetermined sequence, or may be variable.

Further, the ejection means is a means different from a heater for ejecting ink.

FIG. 2 is a block diagram of a control system of an inkjet recording apparatus according to the present invention.

In FIG. 2, the recording device 11 is a host system 12.
An interface circuit 13 is used to receive image (print) data transferred from a serial image interface (video interface).

The interface circuit 13 converts serially transferred print data into parallel data every 8 bits, and outputs V
The data is stored in the VRAM 15 through the RAM control circuit 14.

The interface circuit 13 also includes a circuit 13a that counts the number of printed dots in print data.

The printed dots are not limited to black dots,
Dots of Y (yellow), M (magenta), C (cyan), clear ink, erasing ink, etc. may be used.

The VRAM 15 is, for example, a 64K x 8-bit dynamic RAM, and stores approximately 200 rasters of print (image) data.

The VRAM control circuit 14 switches between data transfer from the interface circuit 13 to the VRAM 15 and data transfer from the VRAM 15 to the print data transfer circuit 16, and controls the timing of data transfer.

The microprocessor 17 plays a central role in the control of the recording device 11, and the ROM 18 and R
It has built-in AM19, port 20 and timer 21.

The microprocessor 17 includes a portion 19a that stores the total number Nb of printed dots (dots formed by ejecting ink) using the RAM 1'9.

The microprocessor 17 controls the interface circuit 13, the print head control circuit 22, and the print data transfer circuit 16 through the path signal line, and controls the print mechanism section 23 using the port 20.

The print head control circuit 22 copies the print data stored in the shift register 24 in the head 2 to the latch 25 using the latch signal L1, and time-divisionally controls the head 2 via the head driver 26 using the drive signals HEO to HE 3. Drive.

The print data transfer circuit 16 reads, for example, 128 bits of print data stored in the VRAM 15 in the vertical direction and transfers it to the shift register 24 in the head 2 . The data number of 128 bits corresponds to the number of dot forming elements (printing elements) of the head 2, that is, the number of energy generating means 27 for ejecting ink.

The microprocessor 17 via the port 20
Controls the printing mechanism section 23.

The printing mechanism section 23 includes a recording medium feed (conveyance) motor, a carriage motor, a discharge means drive motor, and the like.

FIG. 3 is a flowchart showing the operation of the ink jet recording apparatus according to the present invention equipped with the control system shown in FIG.

In FIG. 3, when the printing operation starts, step 1
01 receives image data for 1 raster, and step 1
At step 02, the number of printed dots in the image data is counted by the counter 13a, and the value is added to the total number of printed dots Nb.

Next, in step 103, the image data is converted into 128 rasku (
It is determined whether or not the number of rasters corresponding to the number of ejection ports of the print head has been received.

If it has not been received yet, return to step 101 and repeat the above operation; if it has been received, proceed to step 104, move the carriage 3 to scan, and transfer the print data to the recording head 2 in step 105. death,
In step 106, the dot forming elements of the recording head 2 are driven to form a recorded image on a recording medium such as paper.

In step 107, it is determined whether printing for one line has been completed, and if not, the process returns to step 104 and the above operations are repeated.

If printing for one line has been completed in step 107, the process proceeds to step 108, where it is determined whether the total number of printed dots Nb has reached the number Np that requires ink to be discharged from the ejection ports.

If the number of printed dots reaches the set value Np, step 1
In step 09, the carriage 3 is moved to the home position, in step 110, the ejection means is driven (such as suctioning and ejecting ink from each ejection port), and in step lll, the number of printed dots (counter value) Nb is reset to O. After that, the recording medium is fed in step 112, and step 1
At step 13, it is determined whether printing for one page has been completed.

In step 108, the total number of printed dots NbfJ<setting value Np
If the recording medium is not exceeded, step 112 is performed and the recording medium is fed, and the process proceeds to step 113.

If printing for one page has been completed in step 113, the printing operation is terminated, and if printing for one page has not yet been completed, the process returns to step lot and the above steps are repeated again.

FIG. 4 shows the configuration of a print density evaluation circuit built in the interface circuit 13 of the control system in another embodiment of the inkjet recording apparatus according to the present invention.

The print density evaluation circuit shown in FIG. 4 includes an up/down counter 31. It includes a comparator 32, a D flip-flop 33, and an output buffer 34.

In FIG. 4, image data from host system 12 (FIG. 2) is sent by an image data signal VDO and a clock signal VDOCK.

In the case of black printing, the up/down counter 31 is II!
f'H1, counts down when the data is black, and counts down when it is not printed (white background). Therefore, the count value becomes thicker as the printed dots continue.

Comparator 32 compares the output value of counter 31 and the output value of D flip-flop 33. The D flip-flop 33 stores the output value of the counter 31 when the output value of the counter 31 is larger than its own value.

Therefore, the D flip-flop 33 stores the maximum value of the output of the counter 31 during one raster.

The output value of the D flip-flop 33 is transferred to the output buffer 34.
The data is read out to the microprocessor 17 through the microprocessor 17.

Signal OE is an output control signal for output buffer 34.

According to the inkjet recording apparatus equipped with the print density evaluation circuit of FIG. 4 described above, the up/down counter 31
The number of printed dots is measured, and when the measured value reaches the set value, the ejecting means is driven, so even if the number of printed dots is the same, when the dots are concentrated, they are ejected earlier than when they are dispersed. The means are driven.

Therefore, in this embodiment, when the number of printed dots is large and the printed dots are distributed with a concentration higher than a certain level, this is detected and discharged early. Otherwise, the discharge interval is longer. be done.

In this way, an inkjet recording device is obtained that can prevent a decrease in printing speed and prevent wasteful consumption of ink.

Note that as a method for discharging ink from the ejection port, in addition to the method of suctioning ink from the front surface of the head with a suction pump as in each of the above embodiments, there is also a method of discharging ink from the ejection port. This can also be carried out by a method in which a pump or the like is provided to discharge the ink under pressure.

FIG. 5 is a flowchart of a recording operation in which the drive interval of the ejection means is determined according to the degree of concentration of printed dots using the interface circuit of FIG. 4.

In FIG. 5, when the printing operation is started, step 2
Receive image data for one raster at step 01, and step 2
At step 02, the counter 13a counts the number of printed dots in each image data, and adds that value to the total number of printed dots Nb.

Next, in step 203, the correction value by the print density evaluation circuit as shown in FIG. 4 is added to the total number Nb,
In step 204, the image data is transferred to the number of rasters (for example, 12
8 rasters) has been received.

If data for the number of rasters has not been received yet, the process returns to step 201 and the above steps are repeated.

If data for the number of rasters has been received, step 205
While moving the carriage 3 and scanning, the print data is transferred to the print head 2 in step 206, and the dot forming element of the print head 2, that is, the energy generating means for ejecting ink is driven in step 207. An image is formed (recorded) on a recording medium.

In step 208, it is determined whether or not one line of printing has been completed, and if not, the process returns to step 205 and the aforementioned printing operation is repeated, and when one line of printing has been completed, step 209
Then, it is determined whether the total number of printed dots Nb has reached the number Np that requires ejection of ink from the ejection ports.

When the number of printed dots reaches Np, the carriage 3 is moved to the home position in step 21O, and step 21
In step 1, the ejection means is driven (operations such as suctioning ink from each ejection port or ejecting ink by pressurizing the ink in the ink supply path leading to each ejection port), and step 2
After the number of printed dots (counter value) Nb is reset to 0 in step 12, the sheet is fed in step 213, and it is determined in step 214 whether printing for one page has been completed.

If the number of printed dots Nb has not reached the set value Np in step 209, the recording medium (paper, etc.) is fed by jumping in step 213, and the process proceeds to step 214.

If printing for one page is completed in step 214, the printing operation is terminated; if printing is not completed yet, the process returns to step 201 and the above steps are repeated again.

FIG. 6 is a block diagram showing yet another configuration example different from that in FIG. 4 of the print density evaluation circuit provided in the interface circuit 13 in FIG. 2.

In FIG. 6, 41 is an addition constant, 42 is a subtraction constant, 43 is a selector, 44 is an adder, and 45 is a subtraction constant.
is a D flip-flop, 46 is a comparator, 47
indicates a D flip-flop, and 48 indicates an output buffer.

The selector 43 selects the set value N of the addition constant 41 when the image data is to be printed, and selects the subtraction constant 4 when the image data is not to be printed.
Select the setting value of 2-M.

Therefore, the value of the D flip-flop 45 is
Each non-printed item is counted as 10N, and each non-printed item is counted as -M. These setting values N and -M are set, for example, to +3, -2, etc., but these can be varied by registers, switches, etc.

Therefore, the relationship between the degree of continuity of printed dots and the degree of increase/decrease of the D flip-flop 45 can be freely set.

Comparator 46 and D flip-flop 47 in FIG.
, the output buffer 48, etc. are substantially the same as the comparator 32, D flip-flop 33, output buffer sofa 34, etc. in FIG.

In this case, regarding the degree of concentration of printed dots, when printing data is horizontally developed as a dot image and received serially, the register is set to 1N for printed dots, and -M for non-printed data.
If the maximum value of the register in one raster exceeds a certain value, it is determined that the number of dots is concentrated.

As explained above, the present invention evaluates the number and concentration of printed dots in print data in a recording device, and determines the drive interval of the ejection means for removing air bubbles from the ink based on this evaluation. Therefore, it is possible to control the driving interval to always optimize it, and an inkjet recording apparatus that can prevent a decrease in printing speed and suppress the ink droplet "Rffl" to the necessary minimum has been obtained.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, ink is supplied to a recording head having an ejection port, and energy generating means for ejecting ink provided in the recording head is driven based on print data. Accordingly, in inkjet recording ii in which a recorded image is formed on a recording medium by ejecting ink droplets from the ejection opening, there is provided a means for receiving print data, and a means for receiving print data and determining the number of print dots or the distribution state of print dots in the received print data. a means of measuring;
Since the configuration includes a discharging means for discharging ink from the ejection opening, and a means for controlling the drive of the discharging means based on the number of printed dots or the distribution state of printed dots, it is possible to respond to changes in printing conditions. An inkjet recording apparatus is obtained in which the drive interval of the ink discharge means can always be maintained at an optimum level, thereby preventing a decrease in printing speed and eliminating wasteful consumption of ink.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of an inkjet recording apparatus embodying the present invention, FIG. 2 is a block diagram of the control J11 system of the recording apparatus shown in FIG. 1, and FIG. Flowchart, FIG. 4 is a block diagram of a printing density evaluation circuit in another embodiment of the present invention, FIG. 5 is a flowchart of a recording operation of an inkjet recording apparatus using the evaluation circuit of FIG. 4, and FIG. 6 is a block diagram of a printing density evaluation circuit according to another embodiment of the present invention. FIG. 6 is a block diagram of a print density evaluation circuit in still another embodiment of the present invention. 2-------1 recording head, 3----...--
Carriage, 9-------- Ink supply tube, 10--- Discharge means (suction pump)
, 13---------1.-interface circuit,
13a ----Print dot counter, 19a ----Total number of printed dots (Nb) storage section, 31 --------・Amplifier down counter, 41−・−・−・・Addition constant (+N), 42 −・−1−−−−・−Subtraction constant (−
M). Agent Patent Attorney Yasushi OotoFigure 3

Claims (1)

[Claims] (1) Ink droplets are ejected from the ejection ports by supplying ink to a recording head having an ejection port and driving energy generating means for ejecting ink provided in the print head based on print data. An inkjet recording apparatus that forms a recorded image on a recording medium by means of a means for receiving print data, a means for measuring the number of print dots or a distribution state of print dots in the received print data, and a means for discharging ink from the ejection port. An inkjet recording apparatus comprising: an ejecting means for ejecting ink; and means for controlling driving of the ejecting means based on the number of printed dots or the distribution state of the printed dots.